Rheology of surfactant solution Nonlinear extension of tread like micelles and shear induced structure

研究了十六烷基三甲基溴化铵(CTAB)和钙化钠(NASA)水溶液的非线性流变性，以研究线状胶束的有限延伸性和剪切诱导结构。十六烷基三甲基溴化铵的浓度固定在0.1moL L；鼻塞米松的浓度在0.07~0.4moL L。对于所有的测试方案，用具有单一松弛时间τ的麦克斯韦模型来描述动态模数。测量了定常剪切流开始后剪切应力σ和第一法向应力差N1的时间演化。对于鼻腔浓度较低的溶液，当剪切速率σ超过γ^&lt；-1&gt；时，出现应变硬化，τ和N_1在某一应变处发散。对于鼻腔浓度较高的溶液，在τ^-lt；-1&gt；和一定的临界速率γc之间观察到与普通缠结聚合物溶液相似的应力超调，而在γ&gt；γc处观察到应变硬化。对于弹性固体，N_1/σ=γ是剪切流动施加的应变，在应变硬化区域的所有溶液中都适用一个简单的关系式：N_1/γ。应变硬化可归因于应变相关的剪切模数，并可用考虑网络股有限延伸性的网络理论很好地描述。在非线性流变测量中，我们发现锥板夹具的材料对流变数据有很大的影响。用玻璃锥板夹具测量的应变硬化行为显著减弱。因此，我们研究了玻璃锥板固定器表面处理的效果。我们发现疏水处理对观察线状胶束溶液的硬化行为是相当有效的。发现剪切流剥离后观察到的剪切诱导结构与表面处理有关。

Nonlinear rheology of aqueous solutions of cetyltrimethylammonium bromide (CTAB) and sodium calicylate (NaSal) were investigated in order to study the finite extensionability of thread-like micelles and the shear induced structure. The concentration of CTAB was fixed at 0.1 mol l^<-1>, and the concentration of NaSal was varied from 0.07 to 0.4 mol l^<-1>. For all test solutions, dynamic moduli were described with the Maxwell model having a single relaxation time, τ. Time evolutions of the shear stress, σ, and the first normal stress difference, N_1, after inception of the steady shear flow were measured. For solutions having low NaSal concentrations, strain-hardening was observed and σ and N_1 diverged at a certain strain when the shear rate, γ, exceeded τ^<-1>. For solutions with high NaSal concentrations, stress overshoot similar to that of ordinary entangled polymer solutions was observed at ^between τ^<-1> and a certain critical rate, γc, while the strain-hardening was observed at γ > γc. A simple relationship for elastic solids, N_1/σ= γ with γbeing the strain imposed by shear flow, held for all the solutions in the strain-hardening regime. The strain-hardening was attributable to the strain dependent shear modulus and well described with the network theory considering finite extensibility of network strands.In nonlinear rheological measurements, we found that the rheological data significantly depend on the material of cone-plate fixture. Strain hardening behavior measured with glassy cone-plate fixtures was remarkably weakened. Therefore, we examined the effect of surface treatments of glassy cone-plate fixtures. We found that hydrophobic treatments is quite effective to observe hardening behavior of the thread-like micelle solutions. Shear induced structure observed after cession of shear flow was found to depend on the surface treatments.